Permethrin is widely recognized as an effective insecticide. It is also widely known that the effectiveness of permethrin diminishes with its exposure to oxygen and ultra-violet rays. Permethrin is used on fruit and vegetable crops for control of insects and is toxic to fish and bees. It is, however, one of the least toxic insecticides to humans and animals.
As a precaution to the health of humans who use permethrin-treated garments for protection against insects, the Environmental Protection Agency limits the amount of permethrin in clothing outerwear to 1.25 grams of permethrin per square meter of fabric. The United States government uses this limited amount of permethrin in selected BDUs for the protection of its troops against disease-bearing insects.
The following description of permethrin and its uses is comprised of excerpts from Health Effects of Permethrin-Impregnated Army Battle-Dress Uniforms, a publication published in 1994 by National Academy Press, Washington, D.C. on the health assessment of wearing BDUs impregnated with permethrin. The assessment was prepared in the National Research Council by a Subcommittee to Review Permethrin Toxicity from Military Uniforms. The assessment found that:
1. "More active military service days have been lost to diseases--many of them transmitted by insects--than to combat."
2. "Controlled experiments in the laboratory and with human volunteers in the field show that clothing impregnated or sprayed with permethrin offers reliable protection against a wide range of vector insects and arthropods, such as mosquitoes, human body lice, tstse flies, and ticks, including Ixodes dammini, the principal vector of Lyme disease and human babesiosis in the United States."
3. ". . . the U.S. Army has proposed using permethrin as a clothing impregnant in battle-dress uniforms (BDUs) to kill or repel insects, ticks, and mites."
4. "To adjust for actual exposure conditions, it was assumed that military personnel would wear the permethrin-treated BDUs 18 hr per day for 10 years during a 75-year lifetime."
5. "Adjusting for the proportion of lifetime exposure resulted in a calculated average daily life time dose of 6.8.times.10.sup..5 mg/kg per day."
6. "The average daily lifetime internal dose for garment workers was calculated to be 3.0.times.10 .sup..5 mg/kg bpdy per day less than half the daily dose calculated for military personnel."
7. ". . . soldiers who wear permethrin-impregnated BDUs are unlikely to experience adverse health effects at the suggested permethrin exposure levels (fabric impregnation concentration of 0.125 mg/cm.sup.2)."
8. "Treatment at the approved dosage remains effective through 35 launderings of the uniform (i.e., beyond the combat life of the uniform) but can be removed by dry cleaning (U.S. Army, 1993)."
9. "According to the U.S. Army, application of permethrin to the BDU cloth at the time of manufacturing provides the most consistent treatment at the approved dosage and will relieve soldiers from the burden of treating BDUs."
10. "EPA-registered aerosol cans of 0.5% permethrin are used by all services."
11. "Initial spraying of a BDU with the aerosol formulation provides a permethrin dosage approximately equal to that of an impregnated uniform that has been washed 25 times."
12. "The Army Clothing and Equipment Board has recommended factory permethrin treatment of all desert BDUs, which are worn by soldiers in such deployments as the Gulf War or by field units in rapid deployments."